Parallel lapping device

ABSTRACT

A LAPPING MACHINE WHEREIN A LAPPING TOOL IS SUPPORTED BY A PARALLELOPIPED STRUCTURE WHICH MAINTAINS A DESIRED LINEAR AND PARALLEL LAPPING FORCE ON THE ENTIRE SURFACE BEING LAPPED AND DURING THE ENTIRE LAPPING OPERATION.

Dec. 14, 1971 w ABERNATHY ETAL 3,626,642

PARALLEL LAPPING DEVICE Filed July 31, 1969 3 Sheets-Sheet 1 ,A 2 I 92 6 I 90 16 e 0 K. 62 ["5 v le 6 68 69 "a? I 88 74 o 73-"' l 82 2 II I 22 5 36 z '1 rlO 52 28 L5 I 26 34 j In 24 H" i I'll I 7 58 William J. Abernathy FIG I William J. Reed John R.Sec||y Lowell G. Snoddy,

INVENTORS.

' ATTORNEY.

Dec. 14, 1971 w, ABERNATHY ETAL 3,626,642

PARALLEL LAPPING DEVICE Filed July 31, 1969 3 Sheets-Sheet 5 William J. Abernathy v William J. Reed John R. Sealy Lowell G. Snoddy,

INVISN'I'URS.

ATT RNEY.

United States Patent Ala.

Filed July 31, 1969, Ser. No. 846,338 Int. Cl. B24b 7/00 US. C]. 51-57 Claims ABSTRACT OF THE DISCLOSURE A lapping machine wherein a lapping tool is supported by a parallelopiped structure which maintains a desired linear and parallel lapping force on the entire surface being lapped and during the entire lapping operation.

This invention relates to machinery for the removal of stock from a work piece and particularly to machine for the dressing, honing or lapping of the surface of a work piece by linear rubbing contact between tool and work piece.

Precise removal of stock of small quantities as by the straight line motion of a lapping tool against a work piece is difiicult in that it is difiicult to maintain even pressure over the whole surface of travel. This is particularly true where interior lapping-of a surface is required and a lap must be extended for some distance into the work piece.

It is an object of this invention to provide a machine which will accomplish linear lapping of surfaces of various configurations and which have not in the past been susceptible to machine lapping.

It is a still further obejct of this invention to provide a lapping machine capable of evenly applying the entire abrasive surface of a lap or lapping tool to a surface of a work piece being lapped.

It is a still further object of this invention to provide a lapping machine wherein curved surfaces having radii of varying lengths may be precisely lapped.

'It is a still further object of this invention to provide a lapping machine capable of providing extremely accurate pressure between lap and work piece in a single plane or in two perpendicular planes.

In accordance with the invention, a first and second rectangular plates are spaced apart in parallel relation and connected together by two sets of relatively stitf leaf springs, one set on each of two opposite sides of the assembly. These springs permit lateral pressure applied to one of the plates to be coupled as purely lateral pressure to the other and the parallel relation of the plates maintained. One of the plates, for example, a top plate is oscillated vertically and a lapping tool afiixed to the bottom plate with a vertical lapping surface positioned to work against a work piece with spring force being applied by the leaf springs. With this configuration, pressure between the lapping tool and the work piece may be varied, as needed, for different rates of stock removal and the vertical orientation of the lapping tool is not disturbed since the drive and driven plates remain parallel. The reference to vertical orientation is relative to the foregoing arrangement, and any orientation may be equally maintained.

These and other objects, features and advantages of the invention will become more apparent when considered together with the following description and drawings wherein:

FIG. 1 is a pictorial view of a lapping machine according to the invention;

3,626,642 Patented Dec. 14, 1971 "ice FIG. 2 is a side elevation view of a detail of the machine shown in FIG. 1;

FIG. 3 is an elevation view of a lap holder of a lapping machine as illustrated in FIGS. l-S;

FIG. 4 is a side elevation view, partially in section of a detail of the machine shown in FIG. 1;

FIG. 5 is an elevation view of a detail of the machine shown in FIG. 1;

FIG. -6 is a front elevation view, partly in section, of a detail of the machine shown in FIG. 1;

FIG. 7 is a front elevation view of a detail of the machine shown in FIG. 1;

FIG. 8 is a side elevation view of a detail of a modification of the machine shown in FIG. 1;

FIG. 9 is a side elevation view of still another modification of the machine as shown in FIG. 1; and

FIG. 10 is a pictorial view of a detail of the modification shown in FIG. 9.

Referring now to the drawings and initially to FIGS. 14, reference character '10 generally illustrates a device for producing reciprocating vertical motion and typically would be the basic structure of a conventional slotting machine 11. A rectangular drive member 12 is caused to move up and down in short vertical strokes. It is supported and guided by guide formed by grooves 14 and 15 and driven by a motor drive and cam assembly, not shown. Lapping assembly 16 is supported and thus driven by drive member or cam 12 to which is attached a horizontally positioned arm 18.

Force transmission assembly 20 of lapping assembly 16 basically consists of a force receiving plate member 22, a force application plate member 24, and leaf springs 26, 30, 32 and 34. Leaf springs 32- and 34 are positioned to interconnect adjacent edges 36 and 38 of plate members 22 and 24 and leaf springs 26 and 30 are positioned parallel to springs 32 and 34 on opposite sides of force transmission assembly 20 and interconnect adjacent edges 40 and 42 of plate members 22 and 24. The natural configuration of force transmission assembly 20 is generally rectangular and as a feature of this invention, it enables an adjustable force to be applied by lapping tool assembly 44, attached to plate member 24, to work piece 46 which force is a purely lateral force and this lateral quality is maintained with varying degrees of pressure between lap or lapping tool 48 and work piece 46. The face of lap 48 is operated to present a lapping surface which is generally perpendicular to a line parallel with the planes of plate members 22 and 24 and thus as lap 48 and work piece 46 are brought together and lapping force applied, the degree of force is a function of leaf springs 26 and 30, etc. The resulting lateral deflection of tool 48 as the leaf springs deform forces transmission assembly 20 into a solid parallelogram, that is the planes of all opposite sides remain parallel. This insures that the lapwill maintain its orientation with applied lapping pressure. To state it differently, since top plate 22 is maintained in a fixed horizontal plane, force transmission assembly 20 maintains plate member 24 in a horizontal plane precisely parallel to top plate member 22 and thus lapping tool 48, which is positioned perpendicular to bottom plate member 24, provides and maintains a precise vertical lapping surface.

As a means of relieving pressure between lap 48 and work piece 46, as for example, during inspection of the work piece, or a change of laps, relief screw 52 is supported by arm 28, which arm is rigidly attached to plate 22, is threaded into plate 22 (FIG. 4). Thus by tightening screw 52, plate 24 is pushed away from arm 53 and this moves lap 48 back from work piece 46.

Deflection gauge 54 is supported by plate member 22 and measures lateral displacement between plate members 22 and 24 and thus may be used to measure the amount of stock removed by lap 48 which is rigidly connected to plate member 24.

As illustrated in FIG. 1, the lapping operation is on the inside of work piece 46 and in this example involves the lapping of a curved or radiused surface area. This requires that lap 48 be offset from axis 56 of lap holder 58 (FIG. 3). Lap holder 58 is attached to the underside 60 of plate 24 at a position offset with the axis of rotary coupling 62 which connects force transmission assembly to supporting arm 18. Thus by rotation of shaft 64 of rotary coupling 69 the surface 66 of lap 48 is moved about a radius equal to the distance between surface 66 and axis 56 to lap an internal radius in work piece 46. Work piece 46 is supported on a movable like assembly 47 whereby pressure between lap 48 and work piece can be adjusted.

Rotation or oscillation of force transmission assembly 20 can be manually affected by handle operated lever arm 68 attached to collar 69 on shaft 64. Shaft 64 is rigidly attached to plate 22 and is rotatably supported by arm 18.

Referring now to FIG. 5, rotational travel is adjustably limited by means of pin 70 inserted in shaft 64 by spring clip 71. As shaft 64 is oscillated or rotates back and forth the shank 72 of pin 70 limits travel to the distance permitted within opening 73 of bearing 74 in which shaft 64 rotates. By selecting a proper shank size for a pin 70, a desired angular travel may be precisely obtained.

Referring particularly to FIGS. 6 and 7, mechanical and continuous oscillation of force transmission assembly 20 is provided by drive assembly 75. This is accomplished by mounting a drive gear 76 on shaft 77 of slotting machine 11 on which offset stub shaft drive 78 is attached to drive ram 12. Offset stub shaft 78 drives ram '12 by olfset rotation in slot 79 of ram 12. Drive gear 76 turns gear 80 which in turn rotates shaft 81, and tubular shaft 82, shafts 81 and 82 being rotationally interlocked by pin 84. Cam 86 on the upper end of shaft 82 operates lever arm 88 (FIG. 1) which is attached to and oscillates collar 69 and thus force transmission assembly 20 over an angular travel of approximately 3 degrees. Lever arm 88 is spring loaded against cam 86 by means of arm extension 90 and spring 92. To accommodate vertical relative movement between shafts 81 and 82, pin 84 rides in a vertical slot 94 and spring 96 provides a vertical bias between shafts 81 and 82 so that shaft 81 remains vertically fixed while shaft 82 oscillates vertically.

Some adjustment in radius to be lapped may be made by adjustment of the position of lap 48 in lap holder 58. For additional adjustment the lower plate 98 of a force transmission assembly 100 may include an adjustable mounting bed 102 as shown in FIG. 8. By positioning bed 102 for a desired radius and tightening locking screws 104 and 106 in elongated slots (not shown), any desired radius within the range of travel of bed 102 within slot 107 may be achieved. Otherwise the construction of transmission assembly 100 is identical to that of transmission assembly 20.

The machines illustrated in FIGS. 1-8 provide for applying purely lateral abrasive forces along a single line perpendicular to the leaf springs connecting plates 22 and 24. In order to provide and maintain abrasive forces along two perpendicular lateral lines a third plate member is employed in the force transmission assembly 108 as shown in FIGS. 9 and 10. In it a first set of leaf springs 110 interconnect top plate member 112 and middle plate member 114 to provide a first solid parallelogram or parallelepiped structure and a similar and second set of leaf springs 113 interconnects middle plate member 114 and lower plate member 116, the second set of springs being on sides displaced 90 from the arrangement of the first set of leaf springs. As a result, purely lateral abrasive forces may be applied to lapping tool holder 117 in either of two perpendicular lines of direction as illustrated by the arrows. Deflection gauges 118 and 120, respectively, register deflection in each of the two perpendicular lines of direction, the directions being normal to the faces of leaf springs and 113. Drive and support for transmission assembly 108 is provided through support member 122, not shown in detail. It is believed that the invention described herein provides an improved and novel means for machine lapping and which makes possible precise machine lapping of surfaces not previously possible and practical.

We claim:

1. A lapping machine comprising:

(A) first and second plate members;

(B) coupling means interconnecting and positioning said first and second plate members in spaced parallel relation and including means to permit relative lateral movement only in a single lateral direction to maintain a parallelepiped structure and to provide constrained relative movement in said single lateral direction;

(C) drive means coupled to said first plate member for supporting said first plate member and driving said first plate member along a reciprocating path, which path is perpendicular to the planes of said parallel related plate members; and

(D) tool holding means supported by said second plate member for supporting a lapping tool in a position to provide a lapping surface perpendicular to said single lateral direction of relative movement of said plate members.

2. A lapping machine as set forth in claim 1 wherein said drive means further comprises lapping area control means for selectively moving said first plate member in directions parallel to the common parallel relating to said first and second plate members wherein lapping area may be varied.

3. A lapping machine as set forth in claim 2 wherein said lapping area control means comprises a rotary coupling through which reciprocating drive is axially coupled to said first plate member and further comprising means for rotating said first plate member whereby a radius may be lapped by a lapping tool held by said tool holding means.

4. A lapping machine as set forth in claim 3 wherein said lapping area control means comprises power drive means connected to said rotary coupling for angularly oscillating said first plate member with respect to said drive means.

5. A lapping machine as set forth in claim 1 further comprising work piece holding means for adjustably positioning a work piece being lapped with respect to a tool held by said tool holding means.

6. A lapping machine as set forth in claim 1 further comprising indicating means coupling said first and second plate members for indicating the relative position of said first and second plate members whereby the amount of material removed by lapping is indicated.

7. A lapping machine as set forth in claim 1, further comprising tool relief means interconnecting said first and second plate members and comprising means for adjustably applying force to one of said plate members with respect to the other in opposition to the constraint imposed between said plate members by said coupling means, whereby a tool is adjustably moved away from a work piece being lapped.

8. A lapping machine as set forth in claim 3 wherein said tool holding means includes means for varying the position of a said tool with respect to the axis of said rotary coupling whereby the eccentricity of a tool with respect to said rotary axis may be selectively adjusted.

9. A lapping machine as set forth in claim 1 wherein said coupling means comprises at least two spaced flexible plates interconnecting said plate members being positioned.

10. A lapping machine comprising:

(A) first, second and third plate members;

(B) first coupling means interconnecting and positioning said first and second plate members in spaced parallel relation and including means to permit lateral relative movement only in a first lateral direction to maintain a first parallelepiped structure and to provide constrained relative movement in said (first lateral direction;

(C) second coupling means interconnecting and positioning said second and third plate members in spaced parallel relation and including means to permit relative lateral movement only in a second lateral direction, which second lateral direction is perpendicular to said first lateral direction provided by said first coupling means to maintain a second parallelepiped structure and to provide constrained relative movement in said second lateral direction;

*(D) drive means coupled to said first plate member for driving said first plate member along a reciprocating path which path is perpendicular to planes of said parallel related plate members; and

(E) tool holding means supported by said third plate member for supporting a lapping tool in a position to provide precise linear lapping of surfaces perpendicular to said first and second lateral directions of relative movement of said plate members.

References Cited UNITED STATES PATENTS 2,606,410 8/1952 Thery 5l-59 SS 3,099,853 8/1963 Bills 51-59 3,161,992 12/1964 Gentry et al. 5159 WILLIAM R. ARMSTRONG, Primary Examiner US. Cl. X.R. 

